how do calderas form?

Question

science
(again)

PLEEEEEAAAAASE HELLLLPPPPPPP MEEE!!!

Answer 1

Calderas form when a volcano erupts violently, emptying the magma chamber. The weight of the outer rocks is no longer supported by the magma and they collapse into the volcano creating a caldera.
Yellowstone National Park has 3 calderas from 3 violent eruptions (they overlap each other in many areas). Crater Lake (in Oregon) is a caldera, too.

Answer 2

A caldera collapse is usually triggered by the emptying of the magma chamber beneath the volcano, as the result of a large volcanic eruption. If enough magma is erupted, the emptied chamber will not be able to support the weight of the volcanic edifice (the mountain) above. Fractures will form around the edge of the chamber, usually in a roughly circular shape. These ring fractures may in fact serve as volcanic vents. As the magma chamber empties, the center of the volcano within the ring fractures begins to collapse. The collapse may occur as the result of a single massive eruption, or it may occur in stages as the result of a series of eruptions. The total amount of collapse may be hundreds or thousands of square meters.

Answer 3

http://en.wikipedia.org/wiki/Caldera

Answer 4

Also here is a great site...cheers
http://www.solarviews.com/eng/valles.htm